A landform created by erosion and weathering over time is called a mesa. Mesas are characterized by their flat tops and steep sides, typically found in arid regions. They form when softer rock layers erode away, leaving behind a more resistant layer that creates the flat surface. This geological process can take millions of years, contributing to the stunning landscapes often associated with the American Southwest. Mesas are important in understanding the geological history of an area, as well as the effects of natural forces on the landscape.